Thread reconditioning tool



Se t. 27, 1955 P. B. M KENZIE THREAD RECONDITIONING TOOL Filed April 27, 1955 Paul B. McKenzie IN V EN TOR. @1631.

United States Patent THREAD RECONDITIONING TooL Paul B. McKenzie, Fayetteville, Pa.

Application April 27, 1953, Serial No. 351,130

1 Claim. 01. 10-1 The present invention relates to new and useful improvements in thread reconditioning tools and has for one of its important objects to provide, in a manner as hereinafter set forth, a device of this character which is adapted to be expeditiously mounted at any desired point on the work and then backed off for reconditioning the worn or damaged thread.

Another very important object of the invention is to provide a device of the aforementioned character comprising a multiplicity of coacting dies and which further includes novel means for automatically engaging said dies with the thread after the tool is mounted on the work.

Still another important object of the invention is to provide a device of the character described wherein the torque applied to the tool when unscrewing the same from the work is utilized for maintaining the dies in operative engagement with the thread.

Still another object of the invention is to provide a rethreading tool of the character set forth which includes means for regulating or controlling the cutting depth of the dies.

Still another object of the invention is to provide a thread reconditioning tool of the character described wherein the dies may be readily changed when desired without the necessity of disassembling the device.

Other objects of the invention are to provide a thread reconditioning tool which will be comparatively simple in construction, strong, durable, highly efficient and reliable in use, compact, light in weight and which may be manufactured at low cost.

All of the foregoing and still further objects and advantages of the invention will become apparent from a study or the following specification, taken in connection with the accompanying drawing wherein like characters of reference designate corresponding parts throughout the several views, and wherein:

Figure 1 is a perspective view, showing a thread reconditioning tool in accordance with the present invention with a piece of work engaged therein;

Figure 2 is a view in vertical section through the tool, taken substantially on the line 22 of Figure 1;

Figure 3 is a vertical sectional view at right angles to Figure 2 and taken substantially on the line 33 of Figure 1;

Figure 4 is a view in horizontal section, taken substantially on the line 44 of Figure 2;

Figure 5 is a horizontal sectional view, taken substantially on the line 55 of Figure 2;

Figure 6 is a top plan view of the holder with the dies therein, showing said dies in open position;

Figure 7 is a top plan view substantially similar to Figure 6 but showing the dies in closed position;

Figure 8 is a view in side elevation of the substantially cup-shaped die holder;

Figure 9 is a detail view in side elevation of the rotary die actuator; and

Figure 10 is a detail view in bottom plan of the die ac- 2,718,646 Patented Sept. 27, 1955 tuator retaining ring, showing therein the spring which initiallycloses the dies.

Referring now to the drawing in detail, it will be seen that the embodiment of the invention which has been illustrated comprises a substantially cup-shaped die holder of suitable metal which is designated generally by reference character 12. The holder 12, which may be of anydesired dimensions, includes a relatively thick bottom 13 having formed centrally therein a circular opening 14. Also formed in the bottom 13 of the holder 12 is a diametrically cxtending channel 15 with which the opening 14 communicates. The channel 15 extends to the outer periphery of the holder 12 in a manner to define openings 16 for the insertion and removal of the dies.

Slidable in the channel 15 is a pair of opposed, coacting dies 17. The dies 17 have formed in their upper surfaces cam grooves 18. Formed in the bottom 13 of the holder 12 on opposite sides of the channel 15 and communicating therewith at the ends thereof is a pair of notches or recesses 19. As shown to advantage in Figure 6 of the drawing, when the dies 17 are in open position, the cam grooves 18 are in communication or aligned with the notches 19.

Rotatable in the holder 12 is an actuator 20 or operator for the dies 17. Toward this end, the actuator 20 comprises a tubular shank 21 which is aligned with the opening 14 for the reception of the work, as at 22. The shank 21 includes a polygonal upper portion 23 which is adapted to receive a wrench or other suitable operating tool. Formed integrally with the lower end portion of the shank 21 is a flange 24 which is rotatable on the bottom 13 of the holder 12. Depending from the flange 24 is a pair of lugs 25 which are operable in the cam grooves 18 for opening and closing the dies 17 and for retaining said dies in the channel 15. The lugs 25 are also engageable in the notches or recesses 19 when it is desired to remove the dies 17 from the tool. Rising from the flange 24 is a lug 26. Formed in the periphery of the flange 24 (see Figure 5) is a circumferentially elongated recess 27. The recess 27 is for the reception of a substantially conical stop screw 28 which is threadedly mounted for adjustment in the holder 12 and which positively limits rotation of the actuator 20 in opposite directions in said holder. It may be well to here state that the screw 28 also regulates the depth of the cut of the dies 17 A retaining ring 29 of suitable metal rotatably secures the actuator 20 in the holder 12, said ring encircling the portion 21 of said actuator. Screws 30 removably secured the ring 29 in position in the holder .12 on the flange 24 of the actuator 20. The outer periphery of the ring 29 is provided with circumferentially spaced sockets or depressions 31 in which the screws 30 are engaged. The ring 29 has formed in its lower face an annular groove or channel 32 in which the upstanding lug 26 on the flange 24 is operable. Fixed on the ring 29 in the groove 32 and spaced from the lug 26 is a lug 33. The lugs 26 and 33 constitute abutments with which the ends of a coil spring 34 in the groove 32 are engaged for yieldingly urging the actuator 20 in a direction to close the dies 17. The elements 25, 26 and 33 may be afllxed to the members 24 and 29, respectively, in any suitable manner.

It is thought that the manner in which the tool is used will be readily apparent from a consideration of the foregoing. Briefly, the holder 12 is held in one hand while the actuator 20 is rotated in a clockwise direction with the other hand against the tension of the spring 34, thus opening the dies 17 to receive the work, as at 22. The actuator 20 is then released to be rotated in a counter-clockwise direction by the coil spring 34 for closing the dies 17 on the work. Of course, the dies 17 are actuated by the lugs 25 traveling in the cam grooves 18. The stop screw 28, engageable with the end walls of the recess 27, limits rotation of the actuator 20 to a distance slightly less than the length of the cam grooves 18. A wrench or other suitable tool isthen applied to the polygonal portion 23 of the shank 21 for turning the tool in a counter-clockwise direction for unscrewing the same from the work, thus reconditioning the worn or damaged thread. The turning force thus applied to the tool drives the dies 17 into engagement with the work. By adjusting the substantially conical stop screw 28, the depth of the cut of the dies 17 may be regulated as desired. By backing out or removing the stop screw 28, the actuator 20 may be rotated sufiiciently to engage the lugs 25 in thepockets 19 in the manner suggested in dotted lines in Figure 6 of the drawing. With the lugs 25 thus engaged in the notches or recesses 19, the dies 17 may be readily removed from the holder 12 through the openings 16 for replacement or for any other purpose. Of course, by backing ofi or removing the screws 30, the entire tool may be readily disassembled.

It is believed that the many advantages of a thread reconditioning tool constructed in accordance with the present invention will be readily understood and although a preferred embodiment of the device is as illustrated and described, it is to be understood that changes in the details of construction and in the combination and arrangement of parts may be resorted to which will fall within the scope of the invention as claimed.

What is claimed as new is as follows:

A re-threading tool comprising, in combination, a holder, a plurality of dies slidable in said holder, an operator rotatable in the holder and connected to said dies for opening and closing same, resilient means in the holder for yieldingly urging said operator to die closing position, coacting means on the holder and the operator for adjustably controlling the cutting depth of the dies under the influence of said resilient means, and means for manually actuating the operator for opening the dies, said resilient means including a stationary ring mounted in the holder and having an annular groove therein, a lug on said ring in the groove, a lug on the operator projecting into the groove, and a coil spring mounted under compression in the groove and engaged with said lugs.

References Cited in the file of this patent UNITED STATES PATENTS 827,656 Oster July 31, 1906 936,311 Dundore Oct. 12, 1909 1,044,809 Oster Nov. 19, 1912 1,085,934 Oster Feb. 3, 1914 1,861,538 Leiter June 7, 1932 2,244,138 Brown June 3, 1941 

